1. Field of the Invention
The present invention relates to manipulating the physiochemical properties of water. More particularly, though not exclusively, the present invention relates to a method for using subcritical water to improve the effectiveness of a desired chemical process.
2. Problems in the Art
Throughout the world there is a large need to clean contaminated materials. For example, it is often desired to extract organics as well as nonorganics and metals from solids and semi-solids. Examples include the removal of PAHs, PCBs, pesticides, and metals from soil. Contaminated soil may result from various things including agricultural chemicals, industrial pollution, chemical waste, etc. It is typically difficult and very expensive to remove these contaminants from the contaminated soil. Another example involves the extraction of mercury from contaminated soils. One prior art method of removing contaminants from solids or semisolids involves the use of organic solvents to dissolve the contaminants.
Many industrial processes use organic solvents for separations, reactions, and applications such as applying coatings. Such processes often result in emissions of the solvents and the associated emission control costs.
Another large problem involves the clean up of water. Polluted water or waste water often contains organic or non organic materials which must be removed to clean the water. One common prior art method of removing organics from water involves the use of activated carbon or other suitable sorbents. In an activated carbon filter, water is passed through the filter where the carbon collects the material to be removed from the water. It is well accepted that an activated carbon filter is less effective as the solubility in water of the material to be extracted increases. In other words, the effectiveness of an activated carbon filter is inversely proportional to the solubility of the contaminant in water.
The following references describe background material in detail and are incorporated by reference herein:
Hawthorne, S. B.; Yang, Y.; Miller, D. J., Analytical Chemistry, 1994, 66, 2912.
Yang, Y.; Bowadt, S.; Hawthorne, S. B.; Miller, D. J., Analytical Chemistry, 1995, 67, 4571.
Haar, L.; Gallagher, J. S.; Kell, G. S., National Bureau of Standards/National Research Council Steam Tables; Hemisphere Publishing Corp.: Bristol, PRIOR ART, 1984.
Melander, W. R.; Horvath, C., High Performance Liquid Chromatography--Advances and Perspectives; Vol. 2, Horvath, C., Ed.; Academic Press, Inc.: New York, 1980, pp 113-319.
Features Of The Invention
A general feature of the present invention is the provision of a method for manipulating the physiochemical properties of water which overcomes problems found in the prior art.
A further feature of the present invention is the provision of a method of manipulating the physiochemical properties of water to improve the effectiveness of a desired chemical process by using subcritical water.
Further features, objects, and advantages of the present invention include:
A method for manipulating physiochemical properties of water by subjecting the water to temperatures within the range of 100.degree. to 374.degree. C. while maintaining sufficient pressure to the water to maintain the water in the liquid state (these conditions are defined herein as subcritical water).
A method for extracting organics from solids and semisolids using subcritical water.
A method for selectively extracting desired organics from nonaqueous liquids using subcritical water.
A method for selectively separating different organics using sorbent phases in subcritical water.
A method for enhancing reactions by controlling the disassociation constant of water.
A method for controlling the polarity of water.
A method for controlling the solubility of organic compounds and metals in water.
A method for controlling the viscosity of water.
A method for controlling the surface tension of water.
A method for removing organics from water based on lowered solubility upon cooling the water.
A method for removing organics from water using activated carbon under subcritical water conditions.
These, as well as features, objects and advantages of the present invention will become apparent from the following specification and claims.